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Finding the Fourth Proportional to 221.76, 305.99 and 128.51

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Solution

The fourth proportional to 221.76, 305.99 and 128.51 is: 177.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.76 : 305.99 = 128.51 : x
  2. Step 2: Convert to fraction form
    221.76/305.99 = 128.51/x
  3. Step 3: Cross multiply
    221.76x = 305.99 × 128.51
  4. Step 4: Simplify right side
    221.76x = 39,320.60
  5. Step 5: Solve for x
    x = 39,320.60/221.76
  6. Step 6: Final answer
    x = 177.31

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.